Scala example source code file (ParVector.scala)

This example Scala source code file (ParVector.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

collection, combiner, generics, int, lazyparvectorcombiner, newto, parallel, parvector, seq, seqsplitter, t, vector, vectorbuilder

The ParVector.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala
package collection
package parallel.immutable

import scala.collection.generic.{GenericParTemplate, CanCombineFrom, ParFactory}
import scala.collection.parallel.ParSeqLike
import scala.collection.parallel.Combiner
import scala.collection.parallel.SeqSplitter
import mutable.ArrayBuffer
import immutable.Vector
import immutable.VectorBuilder
import immutable.VectorIterator

/** Immutable parallel vectors, based on vectors.
 *
 *  $paralleliterableinfo
 *
 *  $sideeffects
 *
 *  @tparam T    the element type of the vector
 *
 *  @author Aleksandar Prokopec
 *  @since 2.9
 *  @see  [[http://docs.scala-lang.org/overviews/parallel-collections/concrete-parallel-collections.html#parallel_vector Scala's Parallel Collections Library overview]]
 *  section on `ParVector` for more information.
 *
 *  @define Coll `immutable.ParVector`
 *  @define coll immutable parallel vector
 */
class ParVector[+T](private[this] val vector: Vector[T])
extends ParSeq[T]
   with GenericParTemplate[T, ParVector]
   with ParSeqLike[T, ParVector[T], Vector[T]]
   with Serializable
{
  override def companion = ParVector

  def this() = this(Vector())

  def apply(idx: Int) = vector.apply(idx)

  def length = vector.length

  def splitter: SeqSplitter[T] = {
    val pit = new ParVectorIterator(vector.startIndex, vector.endIndex)
    vector.initIterator(pit)
    pit
  }

  override def seq: Vector[T] = vector

  override def toVector: Vector[T] = vector

  class ParVectorIterator(_start: Int, _end: Int) extends VectorIterator[T](_start, _end) with SeqSplitter[T] {
    def remaining: Int = remainingElementCount
    def dup: SeqSplitter[T] = (new ParVector(remainingVector)).splitter
    def split: Seq[ParVectorIterator] = {
      val rem = remaining
      if (rem >= 2) psplit(rem / 2, rem - rem / 2)
      else Seq(this)
    }
    def psplit(sizes: Int*): Seq[ParVectorIterator] = {
      var remvector = remainingVector
      val splitted = new ArrayBuffer[Vector[T]]
      for (sz <- sizes) {
        splitted += remvector.take(sz)
        remvector = remvector.drop(sz)
      }
      splitted.map(v => new ParVector(v).splitter.asInstanceOf[ParVectorIterator])
    }
  }
}

/** $factoryInfo
 *  @define Coll `immutable.ParVector`
 *  @define coll immutable parallel vector
 */
object ParVector extends ParFactory[ParVector] {
  implicit def canBuildFrom[T]: CanCombineFrom[Coll, T, ParVector[T]] =
    new GenericCanCombineFrom[T]

  def newBuilder[T]: Combiner[T, ParVector[T]] = newCombiner[T]

  def newCombiner[T]: Combiner[T, ParVector[T]] = new LazyParVectorCombiner[T] // was: with EPC[T, ParVector[T]]
}

private[immutable] class LazyParVectorCombiner[T] extends Combiner[T, ParVector[T]] {
//self: EnvironmentPassingCombiner[T, ParVector[T]] =>
  var sz = 0
  val vectors = new ArrayBuffer[VectorBuilder[T]] += new VectorBuilder[T]

  def size: Int = sz

  def +=(elem: T): this.type = {
    vectors.last += elem
    sz += 1
    this
  }

  def clear() = {
    vectors.clear()
    vectors += new VectorBuilder[T]
    sz = 0
  }

  def result: ParVector[T] = {
    val rvb = new VectorBuilder[T]
    for (vb <- vectors) {
      rvb ++= vb.result
    }
    new ParVector(rvb.result)
  }

  def combine[U <: T, NewTo >: ParVector[T]](other: Combiner[U, NewTo]) = if (other eq this) this else {
    val that = other.asInstanceOf[LazyParVectorCombiner[T]]
    sz += that.sz
    vectors ++= that.vectors
    this
  }
}